/// <summary>
/// QuadNode constructor
/// </summary>
/// <param name="nodeType">Type of node.</param>
/// <param name="nodeSize">Width/Height of node (# of vertices across - 1).</param>
/// <param name="nodeDepth">Depth of current node</param>
/// <param name="parent">Parent QuadNode</param>
/// <param name="parentTree">Top level Tree.</param>
/// <param name="positionIndex">Index of top left Vertice in the parent tree Vertices array</param>
public QuadNode(NodeType nodeType, int nodeSize, int nodeDepth, QuadNode parent, QuadTreeRenderer parentTree, int positionIndex)
{
NodeType = nodeType;
_nodeSize = nodeSize;
_nodeDepth = nodeDepth;
_positionIndex = positionIndex;
_parent = parent;
_parentTree = parentTree;
//Add the 9 vertices
AddVertices();
Bounds = new BoundingBox(_parentTree.Vertices[VertexTopLeft.Index].Position,
_parentTree.Vertices[VertexBottomRight.Index].Position);
Bounds.Min.Y = -950f;
Bounds.Max.Y = 950;
if (nodeSize >= 4)
AddChildren();
//Make call to UpdateNeighbors from the parent node.
//This will update all neighbors recursively for the
//children as well. This ensures all nodes are created
//prior to updating neighbors.
if (_nodeDepth == 1)
{
AddNeighbors();
VertexTopLeft.Activated = true;
VertexTopRight.Activated = true;
VertexCenter.Activated = true;
VertexBottomLeft.Activated = true;
VertexBottomRight.Activated = true;
}
}
/// <summary>
/// Add the 4 child quad nodes.
/// </summary>
private void AddChildren()
{
//Add top left (northwest) child
ChildTopLeft = new QuadNode(NodeType.TopLeft, _nodeSize / 2, _nodeDepth + 1, this, _parentTree, VertexTopLeft.Index);
//Add top right (northeast) child
ChildTopRight = new QuadNode(NodeType.TopRight, _nodeSize / 2, _nodeDepth + 1, this, _parentTree, VertexTop.Index);
//Add bottom left (southwest) child
ChildBottomLeft = new QuadNode(NodeType.BottomLeft, _nodeSize / 2, _nodeDepth + 1, this, _parentTree, VertexLeft.Index);
//Add bottom right (southeast) child
ChildBottomRight = new QuadNode(NodeType.BottomRight, _nodeSize / 2, _nodeDepth + 1, this, _parentTree, VertexCenter.Index);
HasChildren = true;
}
/// <summary>
/// Update reference to neighboring quads
/// </summary>
private void AddNeighbors()
{
switch (NodeType)
{
case NodeType.TopLeft: //Top Left Corner
//Top neighbor
if (_parent.NeighborTop != null)
NeighborTop = _parent.NeighborTop.ChildBottomLeft;
//Right neighbor
NeighborRight = _parent.ChildTopRight;
//Bottom neighbor
NeighborBottom = _parent.ChildBottomLeft;
//Left neighbor
if (_parent.NeighborLeft != null)
NeighborLeft = _parent.NeighborLeft.ChildTopRight;
break;
case NodeType.TopRight: //Top Right Corner
//Top neighbor
if (_parent.NeighborTop != null)
NeighborTop = _parent.NeighborTop.ChildBottomRight;
//Right neighbor
if (_parent.NeighborRight != null)
NeighborRight = _parent.NeighborRight.ChildTopLeft;
//Bottom neighbor
NeighborBottom = _parent.ChildBottomRight;
//Left neighbor
NeighborLeft = _parent.ChildTopLeft;
break;
case NodeType.BottomLeft: //Bottom Left Corner
//Top neighbor
NeighborTop = _parent.ChildTopLeft;
//Right neighbor
NeighborRight = _parent.ChildBottomRight;
//Bottom neighbor
if (_parent.NeighborBottom != null)
NeighborBottom = _parent.NeighborBottom.ChildTopLeft;
//Left neighbor
if (_parent.NeighborLeft != null)
NeighborLeft = _parent.NeighborLeft.ChildBottomRight;
break;
case NodeType.BottomRight: //Bottom Right Corner
//Top neighbor
NeighborTop = _parent.ChildTopRight;
//Right neighbor
if (_parent.NeighborRight != null)
NeighborRight = _parent.NeighborRight.ChildBottomLeft;
//Bottom neighbor
if (_parent.NeighborBottom != null)
NeighborBottom = _parent.NeighborBottom.ChildTopRight;
//Left neighbor
NeighborLeft = _parent.ChildBottomLeft;
break;
}
if (this.HasChildren)
{
ChildTopLeft.AddNeighbors();
ChildTopRight.AddNeighbors();
ChildBottomLeft.AddNeighbors();
ChildBottomRight.AddNeighbors();
}
}
/// <summary>
/// Make sure neighbor parents are split to ensure
/// consistency with vertex sharing and tessellation.
/// </summary>
private static void EnsureNeighborParentSplit(QuadNode neighbor)
{
//Checking for null neighbor and null parent in case
//we recode for additional quad trees in the future.
if (neighbor != null && neighbor.Parent != null)
if (!neighbor.Parent.IsSplit)
neighbor.Parent.Split();
}